Sterilization of surgical instruments and apparatus is an absolutely essential step in the performance of successful surgeries. Where surgical instruments such as knives, scalpels and the like are used, sterilization is facilitated by the fact that such instruments have no moving parts, leaving all operative surfaces exposed to sterilizing solutions and sterilizing steam or other heated gases.
Ophthalmological surgical techniques involve the use of extremely small instruments commonly referred to as “microsurgical instruments.” Many of these instruments not only have moving parts, but have parts that are placed within tubes or other channels. One example of such an instrument is known as a cartridge injector, an instrument used to accept a cartridge within which an intraocular lens (IOL) is folded and placed. A plunger in the injector is then moved through a channel to extend a plunger tip which contacts the lens and forces it through an opening at the end of a cartridge and into an incision formed in the eye.
Another commonly used microsurgical instrument is a microforceps. In this instrument, a pair of opposed surgical steel “strips” extend from a hollow tube. The tube, in turn, is attached to a carriage within the instrument and a handle linkage and mechanism which, when operated moves the carriage and, thereby, the tube forward to contact the two surgical steel strips to force them together. When the handle mechanism is relaxed, the tube is allowed to move rearwardly and the strips then separate.
Instruments such as the cartridge injector and microforceps are expensive and are not easily manufactured to be disposable which means that each must be cleaned and sterilized between uses. Because of their sizes and precise construction they are not easily disassembled to facilitate sterilization.
Both instruments are commonly used with a surgical procedure known as phacoemulsification in which an incision is made in the eye to remove a damaged or diseased lens by cutting the lens into pieces and then emulsifying and aspirating the lens particles. Thereafter, a foldable plastic IOL is folded, placed into a cartridge, inserted into a cartridge injector which is then operated to force the lens from the cartridge through the incision into the eye as a replacement for the damaged lens than has already been removed.
The microforceps is used to break the damaged or diseased lens into pieces prior to phacoemulsification. As can be appreciated, these instruments are extremely small in size, particularly given the fact that the incision made in the eye is preferably as small as possible to prevent leakage of eye fluid from the wound after surgery. Where such incisions are sufficiently small, they need not be sutured and will heal without appreciable leakage.
The problem of satisfactorily sterilizing and cleaning microsurgical instruments used in phacoemulsification has been addressed in an article entitled “Residual Debris as a Potential Cause of Post-Phacoemulsification Endophthalmitis,” appearing in Eye (Basingstroke), Volume 17, No. 4, published May 2003 and written by T. Leslie, D. A. Aitken, T. Barrie, and C. M. Kirkness. The authors conducted a study of phacoemulsification instruments that had been sterilized to determine whether debris had been left behind after typical sterilization operations. Samples were taken from phacoemulsification instruments and from irrigation and aspiration instruments. Two studies were done, each at a different institution.
In the first study, 62 percent of the instruments were found to be clean, 16 percent were found to be moderately contaminated and 22 percent were severely contaminated. The second study produced similar results.
A third study compared instruments that had been cleaned by an automated flushing system prior to sterilization. Although not completely eliminating contamination, the technique of flushing prior to sterilization decreased the incidence of contaminated instruments. The flushing apparatus used was automatic in operation.
The prior art includes examples of attempts to provide means for flushing surgical apparatus prior to sterilization.
U.S. Pat. No. 5,225,001 (Manni) teaches and describes a single channel scope cleaning method and apparatus used to pump sterilizing solution through instruments used for endoscopy and arthroscopy. The cleaning apparatus is placed concentrically about the exterior surface of the probe and sterilizing solution is pumped through the cleaning apparatus and through the channel formed between the cleaner and the endoscopic apparatus.
U.S. Pat. No. 5,279,317 (Bowman) teaches and describes an endoscopic cannulated instrument flushing apparatus for forcing a flushing liquid through an endoscopic cannulated instrument for removal of gross debris. The instrument described in Bowman et al has a handle at one end and a surgical tool, such as a pair of gripping arms, at the other. The handle end remains outside the body while the tool end is inserted through an incision and comes into contact with tissue.
The apparatus has a flushing chamber into which the tool end of the instrument is inserted in a friction fit. Sterilizing flushing fluid is forced into the chamber and through the tool end of the endoscopic instrument to exit out of the handle end. The flow of the flushing liquid is thus from the tool end to the handle end, pushing any debris along the entire length of the instrument, requiring a passage large enough to allow such debris to travel all the way to the handle.
U.S. Pat. No. 5,511,568 (Bowman et al) teaches and describes an endoscopic cannulated instrument flushing apparatus for forcing a flushing liquid through an endoscopic cannulated instrument for removal of gross debris. This patent is a continuation-in-part of the earlier mentioned Bowman et al patent and adds a pressurized source of flushing liquid rather than a hand-operated syringe. As with its parent, the cleaning is done in a direction away from the tool end of the instrument.
None of these references are concerned with microsurgical instruments.
Cartridge injectors have narrow and elongated housings through which a plunger is reciprocated to enter an IOL-holding cartridge and force the IOL out of the cartridge and through an incision into the eye.
Microforceps of the type described herein have pair of surgical steel strips which are placed in face-to-face relationship and along a portion of which a tubular housing is moved or reciprocated during surgery. It is this movement along the protruding surgical strips that may trap debris.
In both cases, the clearance between the outer tubular housing and the plunger or surgical strips is small and any debris trapped therewithin is not only a source for potential infection during a subsequent surgical procedure, but also a source of friction during surgery between moving parts of the respective instruments. This friction changes the “feel” of the instrument to the surgeon because of the extremely small operating field can have a serious effect on the surgery.
The microforceps and cartridge injectors described above are representative of microsurgical instruments which may differ in construction from those described herein but which exhibit the same problems when it comes to cleaning the instruments to remove surgical debris prior to sterilization.